1. Field of the Invention
The present invention lies within the realm of devices for the injection molding of materials, in particular plastic parts. The invention lies particularly with the realm of injection-molding devices having a rotation device for rotating one or more center blocks in an injection-molding device according to the pre-characterizing clause of the independent patent claim.
2. Discussion of Related Art
Injection-molding devices for injection molding having one or more rotating center parts which are rotated by 90° or 180° about an axis are known from the prior art. These are used, for example, for the efficient production of multi-component plastic parts. At least one rotatable center part (center block) is provided between two clamping plates for first and second mold halves which can be moved along tie bars in opposite directions. The center block is preferably movably mounted on the tie bars and/or with respect to a machine bed by means of a holding device, and is arranged so that it can be rotated about an axis of rotation by means of a rotation device. The rotatable center block has at least two side surfaces for accommodating third mold halves, which act together with the first and the second mold halves to form cavities. In certain embodiments, the rotatable center block can act together, at least on one side, with a further rotatable center part.
In order to guarantee operation, it is usually necessary for the rotatable center part to be continuously supplied with one or more media while the device is being operated. These can include water, air, oil and electrical power or data, e.g. in the form of measured values. One problem is that one or more media have to be transferred from the stationary holder to the rotatable center part. With the devices disclosed in the prior art, liquid or gaseous media are transferred by means of annular grooves which are arranged parallel and adjacent to one another on a shaft and/or in a correspondingly formed bore, and which are separated from one another by seals. In total, more than 20 circuits can be necessary in order to ensure an adequate supply of media.
One problem with the transfer devices disclosed in the prior art is that they are comparatively large and have a complex structure. Frequently, transfer devices, which project significantly over the rotatable center part and therefore take up a large amount of space, are arranged below and above the center part.
WO9928108 by the same applicant is concerned with a holding device for a rotatable center part. The holding device has two cross members which are supported on tie bars and each carry a rotation unit. A rotatable center part can be clamped between the rotation units. Media are transferred via the axis of rotation of at least one rotation unit which is arranged outside the rotatable center part.
WO08043641 A1 (U.S. Pat. No. 7,922,477) has been filed in the name of the company Sidel and describes a form of rotation device for a horizontal injection-molding machine. The rotation device comprises a base plate, on which is mounted a rotary table which can be rotated about a vertical axis, and drive means for rotating the rotary table. The rotation unit has a plurality of media lines which are arranged in the interior of the axis. An object is to reduce the size and volume of the rotation device.
U.S. Pat. No. 6,132,201 has been filed in the name of the company Husky and describes an injection-molding machine. A center part is rotatably arranged about a horizontal axis. In FIG. 2, a rotatable multiple distributor is arranged at the side next to and outside the rotatable center part in the manner disclosed in the prior art.
EP0511564 has been filed in the name of the company Krupp Corpoplast and is concerned with a device for blow molding plastic. The device for blow molding a thermoplastic has a heating device for temperature-control of parisons and a blowing device for blow molding the parisons. A cam disc has grooves which are arranged substantially concentrically with respect to a center line. The grooves are used to feed in and also to discharge pressure.
WO2005035218 has been filed in the name of the company Krauss-Maffei Kunststofftechnik AG and is concerned with a horizontal injection-molding machine with rotation device. The rotation device is mounted on a machine bed between the tie bars of an injection-molding machine. The rotation device is arranged in a stationary manner. Although the media feed to the rotatable center part is mentioned on Page 3, the person skilled in the art cannot derive any further relevant details with regard thereto.